Fixes for DBS3 duplicate insertions

1. Update DBS3 error message catch for duplicate insertions
2. Implement a check on Proxy Errors where the uploaded will check in the next polling cycle
   if the blocks were really inserted or not, the polling cycle delay should suffice
   for the block to appear in DBS3 if they were really inserted which is usually
   the case with DBS3 Proxy errors. If they are found as injected then mark them in DBS3Buffer.

Fixes #4673
Merge pull request #4709 from dballesteros7/FixDBS

Fixes for DBS3 duplicate insertions